1. Field of the Invention
The present invention is related to a zooming monocular or zooming binoculars.
2. Description of Related Art
In a known monocular or binoculars, an objective optical system and an eyepiece optical system are necessarily provided. Note that the term "binoculars" referred to hereinafter includes both the binoculars and the monocular. Zooming binoculars of a conventional type have at least one variable power lens group in their objective optical system. In this conventional type binoculars, since a field stop (diaphragm) to determine the field of view is fixed (immovable in the optical axis direction), even though the contour of the field stop is made clear at a specific focal length (magnification), the contour of the field stop becomes unclear at other focal lengths. Due to this unclear contour of the field stop, the circumferential portion of the field of view is dimmed.